A microwave-enhanced, solventless Mannich condensation of terminal alkynes and secondary amines with para-formaldehyde on cuprous iodide doped alumina

A microwave-enhanced, solventless Mannich condensation of terminal alkynes and secondary amines with para-formaidehyde on cuprous iodide doped alumina has been developed. beta-Aminoalkynes are generated in good yields. The reaction can be extended to include a cyclization, which affords 2-substituted benzo[b]furans. The chemoselectivity of the reaction indicates that terminal alkynes are much more reactive than enolizable ketones under the reaction conditions. (c) 2005 Elsevier Ltd. All rights reserved.